Method of making pyroxylin solutions of low viscosity



Patented June 24, 1930 UNITED STATES PATENT OFFICE HAROLD HIBIBERT, or MONTREAL, QUEBEC, CANADA, AND JOHN L. rAnsoNs, or ERIE,

PENNSYLVANIA, ASSIGNORS TO HAMMERMILL PAPER COMPANY, or ERIE, PENN- SYLVANIA, A CORPORATION or PENNSYLVANIA METHOD OF MAKING IP YROXYLIN S OLUTIONS OF LOW VISCOSITY No Drawing.

The method of nitrating cotton and other cellulosic materials for the production of pyroxylin lacquers and varnishes is one well known in the arts. Amarked drawback in the industrial application of such solutions to the manufacture of lacquers, varnishes and paints, lies in the fact that in general, the solution formed when the nitrated cellulosic material is dissolved in a suitable organic solvent, such as amyl acetate, has a high viscosity, which makes it impossible to increase the content of nitrated product to the amount desired. Furthermore, such solutions frequently are found immiscible with the usual thinners such as gasoline, benzene, toluene, etc.

The present invention relates to a new process for the production of pyroxylin solutions oflow viscosity, thus providing a means-of producing solutions of much higher concentration of the nitrated cellulosic material. Such solutions are capable of dilution in large volume by the customary thinners.

The process employed consists in a prior treatment of the cellulosic material by means of a small quantity of a suitable oxidizing agent such as permanganates, hypochlorites, peroxides, etc., whereby its character is changed to a remarkable degree so that on nitration the resulting nitrated product gives, when dissolved in the customary organic pyroxylin solvents, solutions characterized by very low viscosities. By relatively slight variations in the nature of the oxidizing agent used, and the condtions under which the same is carried out, it is possible to obtain pyroxylin solutions of widely difi'erent viscosities.

It is now recognized that in the manufacture of pyroxylin paints the pigment used exerts a marked influence on the nature of the resulting pyroxylin paint.

The process as outlined below makes it possible to change the viscosity of the pyroxylin solution to the extent desired on account of the alteration introduced by the addition of the pigment, resin, etc., added in the usual process of manufacture.

The following is one example illustrating the method employed, but it is to be understood that we do not limit our method to this Application filed June 8, 1926. Serial No. 114,559.

one description, and the conditions relating to temperatures, neutrality, alkalinity and acidity of the solution employed during the oxidation are capable of variation within wide limits.

Example One pound of ordinary surgical cotton is suspended in a dilute, slightly alkaline, solution of potassium permanganate containing" between 0.3 and 30 grams of potassium perusual Washing and customary purification, is

dissolved in an organic solvent, such as amyl acetate, yielding a solution characterized by very low viscosity as compared with that of the original nitrated cotton.

We do not limit ourselves to the use of permanganates; other oxidizing mediums such as hypochlorites, peroxides, chromates, etc.,

may be employed and the temperature, alkalinity and acidit may be varied within wide limits. Prefera ly, however, the oxidizing medium is either slightly alkaline, in accordance with the above example, neutral, or slightly acid. Also, while the above example specifies cotton as the starting cellulosic mate rial, we may use instead of cotton, wood pulp material, a mixture of wood pulp material with cotton, or any other suitable cellulosic material;

Various uses of our invention are possible and many modifications may be made in the process which we have described.

We are aware that in bleaching cellulosic materials (such as cotton and wood pulp) as heretofore carried on, some slight oxidation takes place as a necessary and unavoidable incident to the operation. That is to say, it is impracticable to carry on the bleaching operation in such away as to. oxidize the impurities to the desired extent without slightly controlled conditions andto a controlled extent.

By the term cellulosic material used in certain of the claims we mean the more or less impure commercial cellulose resulting from manufacturing processes which are generally employed in the isolation of vegetable fibers from raw fibrous materials. By

I cellulosic materiallis understood the type represented by commercially purified cotton, straw and wood pulp, etc. This term does not include such substances of more or less definite composition as alkali-cellulose, nitrocellulose, etc., which are obtained by allowing cellulosic material to react with chemical reagents.

What we claim-is:

1. In a process for the. production ofa low viscosity solution of a nitrated cellulosic material in an organic solvent, the step of subjecting the cellulosic material before nitration to an oxidation treatment to imparta low viscosity to the final solution, said oxidation being conducted in a medium which may vary in character from slight alkalinity to slight acidity.

2. In a process 7 viscosity solution of a nitrated cellulosic material in an organic solvent, the step of subjec ting the cellulosic material before nitration to an oxidation treatment in a slightly alkaline medium to impart a low viscosity to the final solution;

3. In a process for the production of a low viscosity solution of a nitrated cotton ma terial in an organic solvent, the step of subjecting the cotton material before nitration to an oxidation treatment to impart a low viscosit-y to the final solution, said oxidation be ing conducted in a medium which may vary in character from slight alkalinity to slight acidity.

4. In a process for the production of a low viscosity solution of a nitrated cotton material in an organic solvent, the step of subjecting the cotton material before nitration organic solvent.

6. A process for the production of a loW- first subjecting the said cotton material to a preliminary mild oxidation treatment in a solution of potassium permanganate, then nitrating it, and then dissolving it in-an 7 A process for the production of a low viscosity solution of a. nitrated cotton material in an organic solvent, which comprises first subjecting said cotton material to an oxidation treatment in a solution containing about three grams of potassium permanganate per pound of cotton, then nitrating it and dissolving it in an organic solvent.

8. A process for the production of a low viscosity solution of a nitrated cotton material in an organic solvent, which comprises first subjecting said cotton material to an oxidation treatment in a slightly alkaline solution containing about three grams of potassium permanganate per pound of cotton, then nitrating it and dissolving it in an organic solvent.

. HAROLD HIBBERT. JOHN L PARSONS.

for the production of a low Q to an oxidation treatment in a slightly alkaline medium to impart a low viscosity to the final solution.

'5. A process for the production of a low viscosity solution of a nitrated cotton material in an organic solvent which consists in organic solvent.

then nitrating it, and then dissolving it in an 

